Abstract
Six new divalent metal selenites have been synthesized by hydroโ/solvothermal methods which leads to the incorporation of the organic template as a cation or a ligand. The structure of [H~2~pip][Cu(SeO~3~)~2~] (1) (pip=piperazine) features 1D anionic chains of [Cu(SeO~3~)~2~]^2โ^ which are crossโlinked by the template cations through hydrogen bonds into a 2D layer. In [Cu(C~3~H~4~N~2~)(SeO~3~)] (2) the organic template is coordinated to the copper(II) ion of the inorganic Cu(SeO~3~) layer. The isostructural compounds [H~2~en][M(HSeO~3~)~2~Cl~2~] (en=ethylenediamine; M=Cu (3), Co (4)) contain layers of [MCl~2~(HSeO~3~)~2~]^2โ^ units (M=Cu, Co), which are crossโlinked by the template cations via hydrogen bonds into a 3D network. The structure of [H~2~en][Cu~2~(SeO~3~)~2~(HSeO~3~)]~2~โ
H~2~O (5), consists of a pillared layered architecture in which the Cu(SeO~3~) layers are further interconnected by bridging hydrogen selenite groups (the pillar). The compound [H~2~pip][Cu~2~(Se~2~O~5~)~3~] (6), which crystallizes as a 3D open framework represents the first organically templated metal diselenite. These new compounds are thermally stable up to at least 170โยฐC. All of the compounds exhibit fairly strong antiferromagnetic interactions. More interestingly, compounds 3 and 4 behave as a weak ferromagnets below the critical temperatures of T~c~=12 and 8 K, respectively, and both of them exhibit spinโflop phase transitions around 800ยฑ100 Oe.